After looking around at the speaker market and being overwhelmed by the varied approaches and pricing, I've decided to go my own way. This is going to be a several year long end-game project, though I'm naively starting out with only the most basic knowledge and no experience. Us Eastern Europeans are loony like that.
Approaches:
1. Close to constant directivity down to the bass frequencies by copying Putzey's wide-baffle sealed tweeter/midwoofer arrangement, as per the Grimm LS1
http://www.grimmaudio.com/site/assets/files/1088/speakers.pdf . This requires a waveguide/horn for the tweeter with a low 4th order crossover point to a mid or woofer. I'll go ahead and use a Seas 27DXT tweeter from that design as the graphs (middle of
http://www.grimmaudio.com/site/assets/files/2737/audio_mai_2013_grimm_ls1_testbericht_english.pdf) more than vindicate the choice. However the LS1 wasn't meant to play louder that 105db at 1m and I'd like to be able to go 5-10db higher than that for a decently loud in-room response. The tweeter is crossed of to a 22cm Seas magnesium woofer at 1550hz, I'd like to give it more breathing room and cross at 1900hz to an 18cm Scanspeak slit-paper wonder-woofer that Zaph raves about. I'm not sure about how smooth the transition will be, but even even the LS1's power response shows funkiness around 1-2khz. At 45 degrees off axis it should still be good.
This is where things get tricky: the LS1 design kind of lets everything go to shit in the low-mids and bass, even the LS1s sub is simply a tiny sealed box for a peerless woofer aimed upward and tortured by EQ & raw power to provide an omni response down to 20hz. I'd prefer to crossover to a big ol' dipole woofer, like Marv/Donald do, only at ~300hz. The baffle will be thicker than the LS1's at 60cm vs. 50 cm and I might have to flip the tweeter/mid because of diffraction issues, while keeping all the edges curved. This will give me a 90cm by 60cm region to devote to bass duty, so possible solutions include using two dipole 15" woofers a la Jamo R909 and hoping for useful inroom output down to the 20s, or using one 12-18" dipole crossed over at 40-60hz to a 10-15" sealed sub (or a couple 8-10s spaced horizontally).
Of course this will require a very elaborate cabinet and since I can't woodwork worth a shit (not safely anyway) I'm going to have to whip up a design in CAD and get it CNC'd, preferably in aluminum. Just as with the drivers and digital crossover my solution will be to simply throw money at the problem
As for the crossover, the options include adapting Linkwitz's ASP, a few DSPeaker units or, most likely, DEQX. I don't mind having steep crossovers and time compensation, but I'm going to be rather conservative about EQ, especially above 200hz. Also the sealed subs will make things easy since for my use I won't have any room trouble to correct 'till 50+hz anyway.
Amping using pro-amps or class d modules.
The hope with this design is to have your cake and eat it too. It's an attempt for an end-game rig and probably one I won't get to until figuring out each part of the design on its own.
2. Which brings me to something much cheaper and simpler. Using KEF's coaxial drive units from the LS50 in a sealed-egg type enclosure a la the 207/2. I already have one replacement driver to play with, can buy another one later. Dipole woofers and subs might still be a good idea. I co
uld copy KEF's passive crossover (2nd order?) for the tweeter-mid and use an active crossover at like 200-300 to a sub.
Still complex from a cabinetry point of view, but my hope is to get the KEF egg and basically mount it on (or above) whatever the best bass solution turns out to be.
3. Even more crazy and expensive - rip off Donald North's sealed quad-mid & woofer arrangement using accuton's new Cell 5" & tweeter.
4. Horn. Whole 'nother crazy experimentation-rich field I'd rather not enter unless I have to.
To do list: mess around with speaker/crossover-making software, brush up on drafting. Set up a measurement rig (after moving in the spring) and play around with drivers, use a friend's shop to get some test baffles made.
